1. Field of the Invention
The present invention relates to an apparatus for receiving broadcasting signals, a method of writing data in and/or reading data from a memory device in a broadcasting signal receiving apparatus and an apparatus for receiving broadcasting signals and recording signals based on the received broadcasting signal. The present invention is directed to an improvement in a broadcasting signal receiving apparatus operative to receive a digital audio broadcasting signal for obtaining a reproduced audio signal based on the digital audio broadcasting signal received thereby and as occasion demands to record the reproduced audio signal on a recording medium, an improvement in a method of writing data in a memory device and/or reading the data stored in the memory device therefrom, and an improvement in a signal receiving and recording apparatus operative to receive a digital audio broadcasting signal for obtaining a reproduced audio signal based on the digital audio broadcasting signal received thereby and recording signals containing the reproduced audio signal on a recording medium.
2. Description of the Prior Art
Although an analog audio broadcasting system which includes an amplitude-modulated (AM) audio broadcasting system in which audio signals are transmitted in the form of an AM audio information signal and a frequency-modulated (FM) audio broadcasting system in which audio signals are transmitted in the form of a FM audio information signal, has been put to practical use for a long time in the field of audio broadcasting, there has been recently proposed to introduce a digital audio broadcasting system in which audio signals are transmitted in the form of a digital audio information signal for the purpose of improving quality of audio information transmitted or received in the system. Especially, in the European Continental, the digital audio broadcasting system called "DAB" has been already put to practical use in some countries.
The digital audio information signal transmitted from a broadcasting station under the digital audio broadcasting system is called a digital audio broadcasting signal. The digital audio broadcasting signal carries not only audio information data forming a digital audio signal but also service information data representing service information, such as weather forecast, traffic information and so on, and further carries control information data which are necessitated for reproducing the digital audio signal based on the audio information data and the service information based on the service information data on the receiving side. Each of the audio information data and service information data contain usually various kinds of program information data representing program information of different kinds.
Each of the audio information data and service information data contained in the digital audio broadcasting signal are transmitted in the form of a series of unit segments each having a time duration of, for example, 24 ms and constituting a logical frame. The logical frame of the audio information data constitutes an audio frame which includes audio data representing the program information and program associated data (PAD) which is related to the program information represented by the audio data and provided to follow the audio data. The program associated data represent, in the form of literal information, information of content of the related program information, for example, in the case where the related program information is music information, the name of a composer, the name of a music, the title of recording media in which the audio data are stored and so on.
Such a digital audio broadcasting signal as described above is received by use of a digital audio broadcasting signal receiver. In the digital audio broadcasting signal receiver, each of digital audio broadcasting signals transmitted respectively from a plurality of broadcasting stations is received selectively through a tuning operation by a tuner and the received digital audio broadcasting signal is subjected to a demodulation and decoding processing in a channel decoder and subjected further to a data selection processing in a program selector so as to produce the service information data and audio information data. Then, the audio information data obtained from the program selector are subjected to a decoding processing in a source decoder so that the audio data forming the digital audio signal are reproduced and the program associated data are obtained, and the service information data obtained from the program selector are subjected to a decoding processing in a decoder so that reproduced service data are obtained. A reproduced audio signal is obtained based on the audio data forming the digital audio signal from the source decoder.
The reproduced audio signal thus obtained in the digital audio broadcasting signal receiver is generally high in its quality and is often not only supplied directly to a speaker for reproducing sound but also recorded on an appropriate recording medium to be preserved. When the reproduced audio signal obtained in the digital audio broadcasting signal receiver is recorded on the recording medium to be preserved, it is desirable that the program associated data related to the reproduced audio signal, which are obtained also in the digital audio broadcasting signal receiver, are recorded on thee recording medium to accompany the reproduced audio signal because the program associated data recorded on the recording medium to accompany the reproduced audio signal are convenient for identifying the reproduced audio signal or recognizing the contents of the reproduced audio signal on the occasion of reading of the reproduced audio signal from the recording medium.
When the reproduced audio signal obtained in the digital audio broadcasting signal receiver are recorded on the recording medium to be accompanied with the program associated data related thereto, it is necessary to derive the program associated data from the digital audio broadcasting signal receiver and store the same temporarily in a memory device. Since the quantity of data of the program associated data obtained in the digital audio broadcasting signal receiver to be related to each program information is relatively large usually, it is required for the memory device, in which the program associated data are stored, to have relatively large memory capacity, and therefore, an expensive device would be used as the memory device.
Further, since the information represented by the program associated data related to each program information represented by the reproduced audio signal contains not only information useful to a user who wants to derive the reproduced audio signal from the recording medium and obtain reproduced sound based on the reproduced audio signal but also information unnecessary to the user, the efficiency of data processing is reduced when the whole program associated data are stored in the memory device to be recorded on the recording medium.